Etanercept in children with polyarticular juvenile rheumatoid arthritis.

Background: We evaluated the safety and efficacy of etanercept, a soluble t umor necrosis factor receptor (p75):Fc fusion protein, in children with pol yarticular juvenile rheumatoid arthritis who did not tolerate or had an ina dequate response to methotrexate. Methods: Patients 4 to 17 years old received 0.4 mg of etanercept per kilog ram of body weight subcutaneously twice weekly for up to three months in th e initial, open-label part of a multicenter trial. Those who responded to t reatment then entered a double-blind study and were randomly assigned to re ceive either placebo or etanercept for four months or until a flare of the disease occurred. A response was defined as an improvement of 30 percent or more in at least three of six indicators of disease activity, with no more than one indicator worsening by more than 30 percent. Results: At the end of the open-label study, 51 of the 69 patients (74 perc ent) had had responses to etanercept treatment. In the double-blind study, 21 of the 26 patients who received placebo (81 percent) withdrew because of disease flare, as compared with 7 of the 25 patients who received etanerce pt (28 percent) (P = 0.003). The median time to disease flare with placebo was 28 days, as compared with more than 116 days with etanercept (P<0.001). In the double-blind study, there were no significant differences between t he two treatment groups in the frequency of adverse events. Conclusions: Treatment with etanercept leads to significant improvement in patients with active polyarticular juvenile rheumatoid arthritis. Etanercep t is well tolerated by pediatric patients. (N Engl J Med 2000;342:763-9.) ( C)2000, Massachusetts Medical Society.